Transfer label

ABSTRACT

The invention is directed to a transfer label material for image transfer, comprising a backing carrier material and a transfer layer, said transfer layer at least comprising an image layer, an adhesive layer and a pigmented layer between the adhesive layer and the image layer, said pigmented layer comprising a binder material, at least one white pigment and at least 0.1 wt. %, calculated on the basis of the pigmented layer, of aluminum powder (dry weight).

FIELD OF THE INVENTION

This application was published in English on Mar. 8, 2001 asInternational Publication Number WO 01/15915 A1.

The invention is directed to a transfer label, based on an imagetransfer system and more in particular on a transfer label that isopaque, and can be applied over pre-existing permanent printed images onsubstrate surfaces.

BACKGROUND OF THE INVENTION

Quite often there is a need for application of a label on a surface thatalready has a pre-existing permanent printing on it, for example a silkscreen printing, which cannot be removed without destructive treatmentof the surface. This need may arise in the case of a container, such asa plastic crate for (beer) bottles or other goods, that is used fordifferent brands or promotional items.

It has already been proposed and applied in practice to glue an opaquepaper or plastic label on top of the pre-existing printed images.

Recently, much attention has been directed to the application of labelsby image transfer to a surface. Image transfer is defined as the processof transferring a reverse printed ink-only image from a backing material(carrier web) onto a receiving surface, such as that of a bottle or acrate.

There is a need for using this system of image transfer in relation toapplying labels over pre-existing permanent printed images. However,this has the problem that the conventional ink-only labels (imagetransfer) generally do not provide sufficient opacity to fully cover andmask the pre-existing print and the color of the article on which thelabel is to be applied. Inclusion of a conventional white layer in thetransfer label based on titanium dioxide, zinc oxide and/orcalciumcarbonate pigments can create problems with the printing of thelabel onto the backing layer and with the transferability of the labelmaterial to the substrate surface. Generally more than two layers ofwhite pigmented ink have to be used, to provide sufficient opacity tomask the pre-existing print and/or the color of the substrate article.

There is a need for preventing possible bleed through from affecting thenew label image. Bleed through of the background color could affecttone, hue and/or brightness of the image. There is a need to preventthis.

There is accordingly a need for an improved label material wherein atleast one opaque layer is present, which serves, among others to hide anexisting imprint, while at the same time providing at least equivalentprocessing characteristics in terms of label printing and transfer.

The invention is directed to a transfer label material for imagetransfer, comprising a backing material and a transfer layer, saidtransfer layer at least comprising an image layer, an adhesive layer anda pigmented layer between the adhesive layer and the image layer, saidpigmented layer comprising a binder material, a pigment and at least 0.1wt. %, calculated on the basis of the dry weight of the pigmented layer,of aluminium powder.

It has been found that adding a relatively small amount of aluminiumpowder to at least one pigmented layer results in an opacity, sufficientto hide an existing underlying printing and/or to prevent bleed throughof the background color. The amount of aluminium powder can be keptquite low, up to 5 wt. %, preferably between 0.1 and 1.5 wt. %.

The aluminium powder may be used as such, or incorporated in a suitablematrix material such as a fat derivative, incluidng but not limited tofats and oils, fatty acids, fatty acid esters and the like.

In view of the printing properties of the pigmented layer it ispreferred to use aluminium powder with a particle size of between 1 and100 μm, preferably between 5 μm and 50 μm.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a substrate surface (1) and a label positioned forapplication.

DETAILED DESCRIPTION OF THE INVENTION

The label materials of the invention can comprise various layers, theessential ones being the removable backing layer, at least one imagelayer, an opaque layer and an adhesive layer. Depending on the use ofthe label, the actual build-up of the label may vary. In the mostsimplistic embodiment the label only consists of the layers describedherein. Generally however, more layers are present. In one embodimentthe image layer can consist of two or more separate layers, eachcomprising different colours. Further it is possible to use more thanone adhesive layer and/or a bonding layer between the adhesive layer andsaid opaque pigmented layer. Also a protective layer may be present ontop of the image layer, between the image layer and the removablebacking layer.

Depending on the structure of the label, it can be utilized for eitherremovable or permanent applications. In particular for use on plasticcrates which hold bottles, it may be advantageous to use removablelabels, more in particular to provide temporary labels for promotionalactivities, or to indicate the brand of the contents, which can varydepending on changing marketing demands.

The various possibilities of label structure can be found in thedocuments cited here after, the said structures being incorporatedherein by way of reference.

In the context of the present invention the term image transfer is usedto define a labelling system, wherein a removable backing layer isreverse printed with a suitable ink and subsequently overprinted withadhesive. Important in the image transfer technique is the absence of atransparent or opaque supporting carrier film on the image, once it hasbeen transferred to the surface. At this stage, the image (label) onlyconsists of adhesive, ink materials, optionally with a clear protectivecoating. A general disclosure of this technique is for example disclosedin WO-A 9005088 and WO-A 9005353. Other embodiments of the imagetransfer system are disclosed in WO-A 9734810, WO-A 0735292, WO-A9735291 and WO-A 9735290, the contents of all six applications isincorporated herein by way of reference.

In the context of the present invention it is also possible to use othertypes of no-label-look materials, such as transparent orsemi-transparent labels having a supporting film layer that isincorporated in the label.

The preferred embodiment of the label and application according to thepresent invention will be described first with references to the figurewhich shows a substrate surface (1) and the label positioned forapplication. The label is printed on a carrier film (10) which may beany thin film, preferably oriented polypropylene or polyester. (14) is aprotective coating which may or may not be employed, depending on theproperties and use of the final label. (12) is a release material whichcoats the carrier film for the purpose of providing a known, low peelforce mechanical separation. It may be silicone which is generallyapplied to the film after the film manufacture. (20) represents all theprinted ink material, which may be permanent or removable, depending onthe desired characteristics.

Depending on the label graphics and opacity requirements the inkmaterials may be as many as eight (8) different colors in one or morelayers, some of which may overlay another. (30) represents a layer ofadhesive. (40) represents the pigmented opaque layer. It is to be notedthat adhesive and opaque layer may be construed from more than onelayer.

Upon application, all of the printed materials are transferred from therelease coated film substrate. The printed ink materials can be vinyl,acrylic, urethane or polyester resin based, or combinations thereof,colored with pigments or dyes. The printed adhesive can be a urethanemodified acrylic, heat activatable adhesive or any other suitable heatactivatable adhesive. For heat activatable adhesive to achieve andmaintain tack quickly it may be necessary to heat the substrate surfacebefore the label adhesive is put in contact with it. In someapplications it is also possible to use a pressure sensitive adhesive.

Many options are available for heating the substrate surface. Convectivehot air, oxidizing flame heaters, gas fired infra-red panels andelectric ceramic panels can all be used.

The method of label application whereby the printed ink materials aretransferred from the carrier film to the substrate surface, utilisingthe tactile characteristics of the adhesive to overcome the bond of theink layer 14 to the release coating 12.

Many types of silicone coated polymer films can be used for the printedcarrier film.

The invention is applicable to various systems of label handling,including, but not limited to reel-to reel systems and magazine fedsystems.

In a reel-to-reel system, conventional web handling techniques can beused to advance the film to present the next label and position itaccurately, utilizing a printed “I” mark to trigger an optical scanningdevice.

Protection of the image against scratching by casual handling as well asinsuring its weatherability when subjected to outdoor storage may beachieved with the application of a protective coating, such as a waterbased acrylic wax emulsion. This can be applied via a roller coaterdevice, which is supplied with coating material through a doctor bladein order to control the amount of coating applied. The coating extendswell past the edges of the label image and seals the edges fromintrusive moisture. It is also possible to have a protective coatingpresent preprinted on the transfer label.

The essential aspect of the invention resides in the use of a pigmentedlayer between the image layer and the adhesive layer. The said pigmentedlayer, preferably opaque, at least consists of an ink resin as a binder,white pigment, the white pigment usually being titanium dioxide, zincoxide and/or calcium carbonate, and aluminium powder. Said aluminiumpowder is present in an amount of at least 0.1 wt. %, more in particularin an amount of between 0.2 and 5 wt. %, calculated on the weight of thepigmented layer.

The ink resin binder for the pigmented layer can be any ink suitable forapplication in image transfer systems, such as solvent based or waterbased acrylic, urethane and the like inks, preferably a water basedacrylic ink.

The invention is now elucidated on the basis of the following examples,which are not intended as limiting the scope of the invention in anyway.

EXAMPLES

Two transfer labels were prepared by rotogravure printing with thefollowing sequence of layers printed onto a siliconised film of OPP:

-   -   1. Protective layer, comprising a transparent acrylic ink    -   2. One or more (up to eight) ink image layers, comprising of        suitable pigmented inks or dyes    -   3. First layer containing white pigment in an acrylic binder    -   4. Two different second layers containing two different white        pigment compositions (one comparative; one according to the        invention) in an acrylic binder    -   5. Binding layer, providing adhesion between white layers and        adhesive    -   6. Heat activatable adhesive layer

The two label variants were then transferred onto the surface of aplastic bottle crate, over an existing silk screen printing.

In the first example the two white layers contained 4 g/m² of whitepigment, TiO₂. Even with this large amount of pigment the pre-existingsilk screen printing could be visually noticed through the label image.Increase of the amount of pigment was not possible in light of thedeterioration of printing and transfer characteristics.

In a second example 0.6 wt. % of aluminium powder, having a particlesize of 15 μm, based on the weight of the said layer, was added. Thelabel was completely opaque and the existing printing could not bevisually noticed through the label image. The printing and applicationcharacteristics were good.

1. Transfer label material for image transfer, comprising a backingcarrier material and a transfer layer, said transfer layer at leastcomprising an image layer, an adhesive layer and an opaque pigmentedlayer between the adhesive layer and the image layer, said pigmentedlayer comprising a binder material and at least two different pigments,one of said two pigments being aluminum powder, said aluminum powderbeing present in a concentration of not less than 0.1 weight percent andnot more than 5 weight percent, calculated on the basis of the pigmentedlayer, said aluminum powder being present in a weight percent which issufficient to provide enough additional opacity to effectively maskprinting on an underlying substrate.
 2. Transfer label materialaccording to claim 1, wherein the transfer layer further comprises aboundary layer between the backing carrier material and the image layer.3. Transfer label material according to claim 1, wherein the aluminumpowder has a particle size between 1 and 100 μm.
 4. Transfer labelmaterial according to claim 1, wherein the pigmented layer contains awater based ink as binder material.
 5. Shaped object, having at leastone surface, being provided with at least one label transferred from atransfer label material comprising a backing carrier material and atransfer layer, said transfer layer at least comprising an image layer,an adhesive layer and an opaque pigmented layer between the adhesivelayer and the image layer, said pigmented layer comprising a bindermaterial and at least two different pigments, one of said two pigmentsbeing aluminum powder, said aluminum powder being present in aconcentration of not less than 0.1 weight percent and not more than 5weight percent, calculated on the basis of the pigmented layer, saidaluminum powder being present in a weight percent which is sufficient toprovide enough additional opacity to effectively mask printing on anunderlying substrate.
 6. Transfer label material according to claim 3,wherein the transfer layer further comprises a boundary layer betweenthe backing carrier material and the image layer.
 7. Transfer labelmaterial according to claim 1, wherein the aluminum powder has aparticle size between 5 and 50 μm.
 8. Transfer label material accordingto claim 2, wherein the aluminum powder has a particle size between 1and 100 μm.
 9. Transfer label material according to claim 7, wherein thepigmented layer contains a water based ink as binder material. 10.Transfer label material according to claim 2, wherein the pigmentedlayer contains a water based ink as binder material.
 11. Transfer labelmaterial according to claim 3, wherein the pigmented layer contains awater based ink as binder material.
 12. The shaped object of claim 5,wherein the transfer layer further comprises a boundary layer betweenthe backing carrier material and the image layer.
 13. The shaped objectof claim 5, wherein the aluminum powder has a particle size between 1and 100 μm.
 14. The shaped object of claim 5, wherein the pigmentedlayer contains a water based ink as binder material.
 15. A transferlabel according to claim 1, in which the pigmented layer comprises up to1.5 wt. % aluminum powder.
 16. Transfer label material according toclaim 1 wherein one of said two pigments is titanium dioxide. 17.Transfer label material according to claim 1, wherein one of said twopigments is zinc oxide.
 18. Transfer label material according to claim1, wherein one of said two pigments is calcium carbonate.
 19. Transferlabel material according to claim 1, wherein one of said two pigments isselected from the group consisting of titanium dioxide, zinc oxide andcalcium carbonate.